Advances and controversies in the diagnosis and management of medullary thyroid carcinoma

Survival in medullary thyroid carcinoma patients who fail to achieve a biochemical cure: implications of postoperative 1-month calcitonin levels and targeted therapy

PURPOSE

The survival rate of patients with medullary thyroid carcinoma (MTC) who fail to achieve a biochemical cure after surgery is reduced. This study aimed to investigate the prognostic factors affecting the survival of MTC patients who do not achieve a biochemical cure after surgery.

METHODS

Cox univariate and multivariate proportional hazard models were used to determine the influence of different variables on overall survival (OS). Pearson's chi-square test was used for categorical variables, and paired t-test was used for continuous variables.

RESULTS

In our study of 277 MTC patients treated between 2012 and 2022, there were 96 with raised postoperative 1-month calcitonin (Ct) levels (0-9.52 pg/ml). The overall survival (OS) rates of patients with high postoperative 1-month Ct values at 1, 3, and 5 years were 97.9%, 94.6%, and 86.8%, respectively. The univariate analysis revealed that patients with a postoperative 1-month Ct > 441.9 pg/ml had a greater risk of mortality than patients with postoperative 1-month Ct values ranging from 9.52 to 73.4 pg/ml (p = 0.043). Subsequent analyses revealed that receiving targeted therapy did not improve the OS of patients with distant metastasis among those with high postoperative 1-month Ct values (p = 0.527).

CONCLUSION

This study confirmed that MTC patients who did not achieve biochemical remission after surgery had an increased risk of death when the Ct level was > 441.9 pg/ml 1 month after surgery. Additionally, for MTC patients who have not achieved biochemical remission and have experienced disease progression or distant metastasis after surgery, the use of targeted therapy does not prolong survival.

Extent of Surgery for Medullary Thyroid Cancer and Prevalence of Occult Contralateral Foci

Importance

Standard treatment for patients with medullary thyroid cancer (MTC) consists of total thyroidectomy with central neck dissection, but the rationale for bilateral surgery in patients with unilateral disease on ultrasonography remains unclear.

Objective

To determine the presence of occult contralateral disease (lesions not seen on preoperative ultrasonography) in patients with MTC as a rationale for total thyroidectomy.

Design, Setting, and Participants

This multi-institutional, retrospective cohort study was conducted from September 1998 to April 2022 in academic medical centers and included patients with MTC who underwent thyroidectomy with preoperative imaging.

Main Outcomes and Measures

The primary end point was the prevalence of sonographically occult foci of MTC in the contralateral lobe among patients with sporadic MTC.

Results

The cohort comprised 176 patients with a median age at diagnosis of 55 years (range, 2-87 years), 69 (57.6%) of whom were female. Genetic testing was performed in 109 patients (61.9%), 48 (27.5%) of whom carried germline RET variants. Initial surgical management consisted of total thyroidectomy (161 [91.0%]), lobectomy followed by completion thyroidectomy (7 [4.0%]), and lobectomy alone (8 [4.5%]). Central and lateral neck dissections were performed as part of initial therapy for 146 patients (83.1%). In the entire cohort of 176 patients, 46 (26.0%) had contralateral foci disease and 9 (5.1%) had occult contralateral foci that were not identified on preoperative ultrasonography. Among 109 patients who underwent genetic testing, 38 (34.9%) had contralateral disease, 8 (7.3%) of whom had occult contralateral disease not seen on preoperative ultrasonography. Patients with sporadic MTC experienced a 95.7% reduction in the odds of having a focus of MTC in the contralateral lobe compared with patients with a germline RET variant (odds ratio, 0.043; 95% CI, 0.013-0.123). When adjusting for age, sex, tumor size, and lymph node involvement, the odds ratio of having contralateral MTC in patients with sporadic disease was 0.034 (95% CI, 0.007-0.116). Among patients who underwent lobectomy alone with postoperative calcitonin levels, 5 of 12 (41.7%) achieved undetectable calcitonin levels (<2.0 pg/mL; to convert to pmol/L, multiply by 0.292).

Conclusions and Relevance

The results of this cohort study suggest that a staged approach involving initial thyroid lobectomy could be considered in patients with sporadic MTC and no contralateral ultrasonography findings, with no further surgery if calcitonin levels became undetectable. Further work using prospective randomized clinical trials to evaluate lobectomy as a biochemical cure in patients presenting with unilateral disease is warranted.

Optimizing Diagnostic Accuracy of Fine Needle Aspiration Biopsy Calcitonin Measurements in Detecting Medullary Thyroid Carcinoma

Background: The optimal cutoff value of calcitonin (Ctn) levels measured using an electrochemiluminescence immunoassay (ECLIA) obtained from the washout fluid of fine needle aspiration (FNA-Ctn) for the diagnosis of medullary thyroid carcinoma (MTC) is currently not established. We evaluated the diagnostic accuracy and clinical utility of FNA-Ctn for the diagnosis and location of MTC in patients with nodular or multinodular goiters. Methods: This was a case-control study nested on a prospective multicenter cohort of patients with nodular or multinodular goiter, normal or elevated serum Ctn, and thyroidectomy indications. Ctn and FNA-Ctn were measured using ECLIA methodology before surgery. From this nested cohort, MTC cases and controls (non-medullary pathology) were identified from the final pathological analysis. Cumulative incidence sampling of controls was randomly performed at a ratio of 1:2. Sensitivity, specificity, and area under the receiver operator curve (AUROC) were calculated for patients and the total number of thyroid nodules. Results: From 1272 patients included in the prospective cohort, 50 MTC cases and 105 controls were included. In this study, 286 thyroid nodules were evaluated (63 MTC and 223 non-MTCs). The median serum Ctn value was significantly higher in cases (525 pg/mL [interquartile range (IQR), 162.5-1.200]) than in controls (1.6 pg/mL [IQR, 0.5-5.6]; p < 0.001). The median FNA-Ctn value was significantly higher in MTC nodules (3.100 pg/mL [IQR, 450-45,200]) than in non-MTC nodules (0.5 pg/mL [IQR, 0.5-0.5]; p < 0.0001). In 11 MTC patients with multinodular goiter, the FNA-Ctn value was significantly higher in non-medullary nodules located in the same lobe where an MTC nodule was diagnosed (p = 0.0002). Overall, the FNA-Ctn AUROC was 0.99 [95% confidence interval, 0.98-1.0], and a threshold of ≥220 pg/mL showed 100% sensitivity and 98% specificity for MTC diagnosis. Conclusions: The use of FNA-Ctn measured by ECLIA showed adequate diagnostic accuracy for MTC diagnosis. Moreover, it may be clinically useful for localization in multinodular goiter when lobectomy is considered. Clinical Trial Registration: Clinicaltrials.gov NCT06067594.

Surgical selection and prognostic analysis in patients with unilateral sporadic medullary thyroid carcinoma

PURPOSE

The extent of thyroid surgery and cervical lymph node dissection of unilateral sporadic medullary thyroid carcinoma (sMTC) is still controversial, and the aim of this study was to investigate whether hemithyroidectomy was adequate as a locally curative surgery for patients with unilateral sMTC.

METHODS

This study is a retrospective case series of patients with sMTC who underwent curative total thyroidectomy or hemithyroidectomy in our institution from January 2011 to December 2019.

RESULTS

In total, 129 patients who met the inclusion criteria were enrolled including 49 (38.0%) patients who underwent total thyroidectomy and 80 (62.0%) patients who underwent hemithyroidectomy. About 80 (62.0%) patients achieved a biochemical cure (BC), whereas there was no significant difference between two groups in biochemical cure rate (61.2% versus 62.5%, P = 0.885). A logistic regression analysis showed a strong negative correlation between the factors of preoperative calcitonin level and pTNM stage and biochemical cure. In the log-rank test, no significant difference in OS (P = 0.314) and DFS (P = 0.409) was found between the two surgical groups. Lateral cervical lymph node metastasis and pTNM stage were significant prognostic factors affecting DFS in univariate analysis; moreover, absence of biochemical cure, tumor size ≥ 4 cm and lateral cervical lymph node metastasis were independent risk factors of unilateral sMTC patients in our analysis.

CONCLUSION

For patients with unilateral sMTC, hemithyroidectomy was adequate as a locally curative surgery, because the patients underwent total thyroidectomy did not benefit more from it in the aspects of BC/OS/RFS, while the postoperative increasing incidence rate of postoperative hypocalcemia could not improve patients' quality of life.

Medullary thyroid carcinoma: a 30-year experience at one institution in Korea

PURPOSE

The objective of this study was to review the clinical outcome and prognosis of patients with sporadic and hereditary medullary thyroid cancer (MTC) who were treated at a single tertiary hospital in Korea.

METHODS

We retrospectively reviewed the case files of 85 patients treated from August 1982 to February 2012.

RESULTS

In all, 65 patients (76.5%) had sporadic MTC and 20 patients (23.5%) had hereditary MTC. Patients in the sporadic group were older than in the hereditary group (P < 0.001). However, the hereditary group had more tumor multiplicity (P < 0.001) and bilaterality (P < 0.001). Neither survival rate was significantly different between the sporadic and hereditary groups (P = 0.775 and P = 0.866). By multivariate analysis, distant metastasis was a significant prognostic factor for overall and progression-free survival.

CONCLUSION

In general, patients with MTC have favorable outcomes. Distant metastasis appears to be the strongest predictor of overall and progression-free survival.

Multifocality in Sporadic Medullary Thyroid Carcinoma: An International Multicenter Study

BACKGROUND

Current surgical standard of care in sporadic medullary thyroid carcinoma (sMTC) consists of a minimum of total thyroidectomy with central neck dissection. Some have suggested thyroid lobectomy with isthmusectomy and central neck dissection for patients with sMTC, given their lower frequency of bilateral disease, although this topic has not been thoroughly studied. This study assessed the prevalence of multifocality in sMTC via a large international multi-institutional retrospective review to quantify this prevalence, including the impact of geography, to assess more accurately the risks associated with alternative surgical approaches.

METHODS

A retrospective chart review of sMTC patients from 11 institutions over 29 years (1983-2011) was undertaken. Data regarding focality, extent of disease, RET germline analysis plus family and clinical history for multiple endocrine neoplasia type 2 (MEN2), and demographic data were collected and analyzed.

RESULTS

Patients from four continents and seven countries were included in the sample. Data for 313 patients with documented sMTC were collected. Of these, 81.2% were confirmed with negative RET germline testing, while the remaining 18.8% demonstrated a negative family history and no manifestations of MEN2 syndromes other than MTC. Bilateral disease was identified in 17/306 (5.6%) patients, while multifocal disease was noted in 50/312 (16.0%) sMTC patients. When only accounting for germline negative patients, these rates were not significantly different (5.6% and 17%, respectively). Among them, when disease was unifocal in the ipsilateral lobe and isthmus, bilateral disease was present in 6/212 (2.8%) cases. When disease was multifocal in the ipsilateral lobe or isthmus, then bilateral disease was present in 8/37 (21.6%) cases (p < 0.001). No geographic differences in focality were identified.

CONCLUSIONS

The 5.6% prevalence of bilateral foci in sMTC suggests that total thyroidectomy should remain the standard of care for initial surgery, as less complete thyroid surgery may fail to address fully the primary site of disease. Whether ipsilateral tumor focality should be an independent factor determining the need for completion thyroidectomy when sMTC is diagnosed after hemithyroidectomy remains to be determined.

Surgery in MEN 2A Patients Older Than 5 Years with Micro-MTC

In multiple endocrine neoplasia syndrome type 2A (MEN 2A), early total thyroidectomy (TT; performed before the age of 5 years) is the best option to prevent medullary thyroid carcinoma (MTC) development, but the management of MEN 2A patients diagnosed after childhood is still under debate. Seventeen consecutive patients diagnosed with MEN 2A after the age of 5 years (mean age, 23.3 years) with a pathologic diagnosis of micro-MTC without nodal involvement were enrolled. All patients underwent TT with thymectomy and central compartment lymph node dissection. During surgery, parathyroid tissue removal occurred in 14 patients. No major postoperative complications nor persistent hypoparathyroidism was observed. After a mean follow-up of 16.6 years, no patient developed primary hyperparathyroidism or disease recurrence. Even if TT is recommended before the age of 5, when MEN 2A diagnosis is performed after this age in micro-MTC without nodal involvement, TT with thymectomy and central compartment lymphadenectomy can provide good oncologic and functional results.

RAS proto-oncogene in medullary thyroid carcinoma

Medullary thyroid carcinoma (MTC) is a rare malignancy originating from the calcitonin-secreting parafollicular thyroid C cells. Approximately 75% of cases are sporadic. Rearranged during transfection (RET) proto-oncogene plays a crucial role in MTC development. Besides RET, other oncogenes commonly involved in the pathogenesis of human cancers have also been investigated in MTC. The family of human RAS genes includes the highly homologous HRAS, KRAS, and NRAS genes that encode three distinct proteins. Activating mutations in specific hotspots of the RAS genes are found in about 30% of all human cancers. In thyroid neoplasias, RAS gene point mutations, mainly in NRAS, are detected in benign and malignant tumors arising from the follicular epithelium. However, recent reports have also described RAS mutations in MTC, namely in HRAS and KRAS. Overall, the prevalence of RAS mutations in sporadic MTC varies between 0-43.3%, occurring usually in tumors with WT RET and rarely in those harboring a RET mutation, suggesting that activation of these proto-oncogenes represents alternative genetic events in sporadic MTC tumorigenesis. Thus, the assessment of RAS mutation status can be useful to define therapeutic strategies in RET WT MTC. MTC patients with RAS mutations have an intermediate risk for aggressive cancer, between those with RET mutations in exons 15 and 16, which are associated with the worst prognosis, and cases with other RET mutations, which have the most indolent course of the disease. Recent results from exome sequencing indicate that, besides mutations in RET, HRAS, and KRAS, no other recurrent driver mutations are present in MTC.

MEN2B syndrome presenting as an acute respiratory emergency

An 18-year-old girl presented to the emergency department with a history of noisy breathing and breathlessness progressively increasing for few days. The patient had stridor and tachypnoea. She was tall with a long thin face, wrist sign and high-arched palate suggestive of marfanoid features. X-ray of the neck revealed critical tracheal narrowing. Emergency tracheostomy was performed as a lifesaving procedure. Non-contrast CT neck revealed extratracheal compression by a mass surrounding it. Contrast-enhanced CT scan of the neck revealed heterogeneous mass arising from the right lobe of the thyroid and tracheal deviation with narrowing. Fine-needle aspiration cytology of the mass revealed medullary carcinoma of the thyroid, positive for calcitonin. Calcitonin levels were raised. Apart from the marfanoid features she had localised swellings over the lips, lower eyelid and the lateral aspects of the tongue, clinically suggestive of neuromas. A clinical diagnosis of multiple endocrine neoplasia type 2B syndrome was made. The patient underwent total thyroidectomy with central lymphnode dissection. This case highlights an unusual presentation of a rare disease.

Advanced medullary thyroid cancer: pathophysiology and management

Medullary thyroid carcinoma (MTC) is a rare malignant tumor originating from thyroid parafollicular C cells. This tumor accounts for 3%-4% of thyroid gland neoplasias. MTC may occur sporadically or be inherited. Hereditary MTC appears as part of the multiple endocrine neoplasia syndrome type 2A or 2B, or familial medullary thyroid cancer. Germ-line mutations of the RET proto-oncogene cause hereditary forms of cancer, whereas somatic mutations can be present in sporadic forms of the disease. The RET gene encodes a receptor tyrosine kinase involved in the activation of intracellular signaling pathways leading to proliferation, growth, differentiation, migration, and survival. Nowadays, early diagnosis of MTC followed by total thyroidectomy offers the only possibility of cure. Based on the knowledge of the pathogenic mechanisms of MTC, new drugs have been developed in an attempt to control metastatic disease. Of these, small-molecule tyrosine kinase inhibitors represent one of the most promising agents for MTC treatment, and clinical trials have shown encouraging results. Hopefully, the cumulative knowledge about the targets of action of these drugs and about the tyrosine kinase inhibitor-associated side effects will help in choosing the best therapeutic approach to enhance their benefits.

Imaging of the thyroid: Recent advances

Although thyroid scintigraphy and ultrasound continues to be the mainstay of the diagnostic imaging of the thyroid gland, there have been several recent advances that are of interest to both radiologists and endocrinologists. In this review article, the authors discuss recent progress in imaging of the thyroid by use of radionuclide imaging including single photon-emission computed tomography/positron emission tomography, ultrasonography (USG), USG elastography, computed tomography (CT), magnetic resonance imaging (MRI), and optical coherence tomography.

Multiple endocrine neoplasias type 2B and RET proto-oncogene

Multiple Endocrine Neoplasia type 2B (MEN 2B) is an autosomal dominant complex oncologic neurocristopathy including medullary thyroid carcinoma, pheochromocytoma, gastrointestinal disorders, marphanoid face, and mucosal multiple ganglioneuromas. Medullary thyroid carcinoma is the major cause of mortality in MEN 2B syndrome, and it often appears during the first years of life. RET proto-oncogene germline activating mutations are causative for MEN 2B. The 95% of MEN 2B patients are associated with a point mutation in exon 16 (M918/T). A second point mutation at codon 883 has been found in 2%-3% of MEN 2B cases. RET proto-oncogene is also involved in different neoplastic and not neoplastic neurocristopathies. Other RET mutations cause MEN 2A syndrome, familial medullary thyroid carcinoma, or Hirschsprung's disease. RET gene expression is also involved in Neuroblastoma. The main diagnosis standards are the acetylcholinesterase study of rectal mucosa and the molecular analysis of RET. In our protocol the rectal biopsy is, therefore, the first approach. RET mutation detection offers the possibility to diagnose MEN 2B predisposition at a pre-clinical stage in familial cases, and to perform an early total prophylactic thyroidectomy. The surgical treatment of MEN 2B is total thyroidectomy with cervical limphadenectomy of the central compartment of the neck. When possible, this intervention should be performed with prophylactic aim before 1 year of age in patients with molecular genetic diagnosis. Recent advances into the mechanisms of RET proto-oncogene signaling and pathways of RET signal transduction in the development of MEN 2 and MTC will allow new treatment possibilities.

Molecular basis of medullary thyroid carcinoma: the role of RET polymorphisms

Medullary thyroid carcinoma is a rare malignant tumor originating in parafollicular C cells. It accounts for 5 to 8% of all thyroid cancers. MTC develops in either sporadic (75%) or hereditary form (25%). Genetic and molecular studies have demonstrated the involvement of the RET proto-oncogene in hereditary MTC and, less often, in its sporadic form. Although a strong genotype-phenotype correlation has been described, wide clinical heterogeneity is observed among families with the same RET mutation or even in carriers of the same kindred. In recent years, several single nucleotide polymorphisms of the RET gene have been described in the general population as well as in patients with MTC. Some studies have reported associations between the presence of polymorphisms and development or progression of MTC. Nonetheless, other studies failed to demonstrate any effect of the RET variants. Differences in the genetic background of distinct populations or methodological approaches have been suggested as potential reasons for the conflicting results. Here, we review current knowledge concerning the molecular pathogenesis of sporadic and hereditary MTC. In particular, we analyze the role of RET polymorphisms in the clinical presentation and prognosis of MTC based on the current literature.

Mixed Medullary-follicular-derived carcinomas of the thyroid gland

Tumors of the thyroid are subclassified based on the cell of origin and commonly include follicular-derived tumors and C-cell-derived tumors. The most common follicular-derived tumors are papillary carcinoma and follicular carcinoma, whereas the malignant C-cell-derived tumor is medullary thyroid carcinoma. Rare cases in the literature describe patients who have follicular-derived and C-cell-derived tumors in the same thyroid gland. These can be synchronous but anatomically separate carcinomas, or they can show some mixing of the 2 components. The mixture may be at an interface, as in collision tumors, or can be throughout the entire lesion, as in true mixed medullary-follicular-derived carcinomas. The clinical, histologic, and molecular features of these mixed tumors and the classification guidelines are reviewed.

Nodular disease and parafollicular C-cell distribution: results from a prospective and retrospective clinico-pathological study on the thyroid isthmus

OBJECTIVE

The isthmus represents a peculiar, as yet partially unexplored, thyroid gland area.

AIM OF THE STUDY

To assess i) the prevalence and clinico-pathological features of solitary thyroid isthmic nodules (STIN); ii) the frequency of medullary thyroid carcinoma (MTC) arising from the isthmus; and iii) the C-cell distribution in the isthmus of patients with MTC and benign nodular thyroid disease (NTD).

SUBJECTS AND METHODS

Patients referred from 2006 to 2008 for STIN were prospectively recruited, and underwent serum calcitonin (C(t)) measurement and fine needle aspiration cytology (FNAC). MTCs diagnosed from 1993 to 2005 were retrospectively searched. Immunohistochemistry was performed using anti-C(t) antibodies on lateral lobes and isthmi of 50 benign NTD and 50 MTC cases.

RESULTS

From 1993 to 2005, 150 patients underwent surgery for MTC. All patients had the neoplasm located in lateral thyroid lobes, none in the isthmus. In the 3 years following, 192 STIN patients (40 (21%) males, 152 (79%) females; mean age: 46.2+/-7.1 years; 6.4% of NTD subjects) were recruited. All had normal C(t) concentrations. FNAC was malignant or suspicious for malignancy in 14 (7.3%) patients. Histology found malignancy in 17 (9%) cases, MTC in none. C cells were disclosed in lateral thyroid lobes of 100% MTC and 77% benign NTD patients; isthmi were free of C cells in either group.

CONCLUSIONS

STINs are significantly less likely to be MTC in patients presenting with sporadic disease. Therefore, C(t) screening is not warranted in these subjects. Nonetheless, STINs are more likely to be neoplastic and deserve equal attention as those of the lateral lobes.

Alternative surgical strategies and favorable outcomes in patients with medullary thyroid carcinoma in Japan: experience of a single institution

BACKGROUND

Medullary thyroid carcinoma (MTC) accounts only for 1.4% of all thyroid malignancies in Japan. Since 1996, we have performed hemithyroidectomy, instead of total thyroidectomy, for sporadic nonhereditary MTC when the primary lesion is located in only one lobe. Regarding lymph node dissection, modified radical neck dissection (MND) at least ipsilateral to the tumor has been routinely performed, even if there is no clinically apparent metastasis. We investigated the clinical outcomes of MTC patients in our department.

METHODS

A series of 118 patients with MTC who underwent initial surgery between 1975 and 2005 were enrolled in this study. The RET gene mutations were analyzed for all patients and 46 had germline RET gene mutations. Of those 46 patients, 26 were diagnosed as MEN 2A and 2 were diagnosed as MEN 2B. Postoperative follow-up periods averaged 141 months.

RESULTS

Of 115 patients who did not have distant metastasis at surgery and who underwent locally curative surgery, 78 (67.8%) were biochemically cured. All patients without pathological lymph node metastasis were biochemically cured, and 44.8% of patients with node metastasis were also biochemically cured. The 10-year and 20-year disease-free survival rates were 89.0% and 82.5%, respectively. None of the patients who did not show lymph node metastasis and only 2 (2.6%) of 78 patients who were biochemically cured showed clinically apparent carcinoma recurrence. The 10-year and 20-year cause-specific survival rates were 96.6% and 91.7%, respectively. Lymph node metastasis, tumor size>4 cm, extrathyroid and extranodal tumor extensions significantly affected cause-specific survival of patients.

CONCLUSIONS

Clinical outcomes of MTC patients in our series were better than those in Western countries, a result that might have resulted in part because of our routine MND regardless of whether clinically apparent node metastasis was detected.

Functional nuclear medicine imaging of medullary thyroid cancer

Medullary thyroid cancer (MTC) originates from parafollicular C cells of the thyroid and accounts for 3-12% of all thyroid cancers. As opposed to other types of dedifferentiated thyroid tumours, MTC cells are highly functional, producing and secreting high amounts of calcitonin and carcinoembryonic antigen. As parafollicular C cells are of neural crest origin, MTC acts as a neuroendocrine tumour also and expresses somatostatin receptors. Although conventional radiological methods such as ultrasonography, computed tomography and magnetic resonance imaging are widely used in the primary diagnosis and staging, they often fail to localize the residual or recurrent disease because the majority of MTC recurrence presents as occult disease. Thus, owing to functional characteristics of MTC, functional imaging modalities of nuclear medicine play a major role in the diagnostic and therapeutic strategies for MTC. Among nuclear medicine modalities, Tc(V) -dimercaptosuccinic acid, In-octreotide and I/I-meta-iodobenzylguanidine are commonly used in the diagnostic and even more in postoperative work-up of MTC. Alternatively, F-fluorodeoxyglucose and other positron emission tomography radiopharmaceuticals such as F-fluorodopa or F-fluorodopamine as well as radiolabelled antibodies such as Tc/I/I anticarcinoembryonic antigen, antigastrin, and anticholecystokinin-B have promising results. Functional imaging has a great advantage for nuclear medicine techniques in the routine work-up of MTC patients and also has a wide use in experimental studies.

Clinical and oncological features of children and young adults with multiple endocrine neoplasia type 2A

BACKGROUND

RET genotype analysis allows identification of asymptomatic carriers at risk of developing medullary thyroid carcinoma (MTC). However, there is still controversy regarding the ideal timing and extent of prophylactic thyroidectomy due to the wide spectrum of clinical presentation. Surveillance of a large number of young patients is crucial to advance our understanding of the natural course of the disease. This study aimed to describe the clinical presentation, oncological features, and treatment outcome of children and young adults harboring RET mutations followed at our institution from 1997 to 2007.

METHODS

Forty-one individuals aged < or =25 years from 17 independent multiple endocrine neoplasia type 2A kindred were studied. Twenty-one individuals presented with thyroid nodules at diagnosis, and 20 were disease free at physical examination.

RESULTS

Preoperative basal calcitonin levels were elevated in 85.7% of patients with clinical disease and in 54.5% of asymptomatic carriers. Thyroid ultrasonography (US) showed one or more nodules in 69.0% of the patients. A positive correlation between age at surgery and tumor-node-metastasis (TNM) stages was observed (p < 0.001). None of the patients under 15 years of age presented lymph node or distant metastasis. After a follow-up of 4.4 +/- 1.4 years all asymptomatic patients were disease free based on physical examination, cervical US, and undetectable serum calcitonin levels. In the group of patients with clinical disease, 47.6% have persistent disease (follow-up of 12.0 +/- 5.9 years). Indeed, palpable thyroid nodule at diagnosis was significantly associated with persistent disease (p < 0.001, odds ratio [OR] 1.9, 95% confidence interval [CI 95%] 1.27-2.87). Of note, none of the patients who presented lymph node metastasis at diagnosis were cured by surgical intervention (p < 0.001, OR 5.0, CI 95% 1.45-17.0).

CONCLUSION

Our data show a time-dependent MTC progression. The presence of a palpable thyroid nodule and lymph node metastasis at diagnosis was associated with persistent or recurrent disease after surgical procedure.

New presentation of familial medullary thyroid carcinoma in 87-year-old patient with high-riskRETproto-oncogene codon 620 mutation

Objective:

We report a case of familial medullary thyroid carcinoma in an 87-year-old woman, despite the patient having a high-risk codon 620 mutation.

Method:

Medline and PubMed were searched for cases and literature reviews relating to the following keywords: ‘codon 620’, ‘medullary thyroid carcinoma’, ‘multiple endocrine neoplasia’ and ‘RET proto-oncogene’.

Results:

We report the case of an 87-year-old woman who presented with a goitre, later identified as medullary thyroid carcinoma. Genetic analysis revealed aRETproto-oncogene codon 620 mutation. Genetic testing has revolutionised the management of medullary thyroid carcinoma. The genetic basis of hereditary medullary thyroid carcinoma lies with theRETproto-oncogene. Several disease-causing mutations of this gene have been identified and their clinical prognosis described. The penetrance of these mutations is high; as such, carriers progress to develop medullary thyroid carcinoma at a young age. Mutations at the codon 620 position are classified as high-risk for early development of medullary thyroid carcinoma; thus, the current recommendation is for prophylactic thyroidectomy at five years of age.

Conclusions:

In this case, the progress of hereditary medullary thyroid carcinoma was unique, considering the late presentation of medullary thyroid carcinoma despite the presence of the high-riskRETproto-oncogene codon 620 mutation. The authors wish to highlight the importance of this case, as it may present a counter-argument to the current recommendations for early, prophylactic thyroidectomy in codon 620 mutation carriers in order to prevent early development of medullary thyroid carcinoma.

The Role of Prophylactic Surgery in Cancer Prevention

BACKGROUND

Since the human genome has been sequenced many mysteries of cell biology have been unravelled, thereby clarifying the pathogenesis of several diseases, particularly cancer. In members of kindreds with certain hereditary diseases, it is now possible early in life to predict with great certainty whether or not a family member has inherited the mutated allele causing the disease. In hereditary malignancies this has been particularly important, because in affected family members there is the possibility of removing the organ destined to develop cancer before malignancy develops or while it is in situ. At first consideration, it would appear that "prophylactic surgery" would have a place in many hereditary malignancies; however, the procedure has applicability only if certain criteria are met: (1) the genetic mutation causing the hereditary malignancy must have a very high penetrance and be expressed regardless of environmental factors; (2) there must be a highly reliable test to identify patients who have inherited the mutated gene; (3) the organ must be removed with minimal morbidity and virtually no mortality; (4) there must be a suitable replacement for the function of the removed organ; and (5) there must be a reliable method of determining over time that the patient has been cured by "prophylactic surgery."

CONCLUSIONS

In this monograph we review several hereditary malignancies and consider those where prophylactic surgery might be useful. As we learn, there are various barriers to performing the procedure in many common hereditary cancer syndromes. The archetype disease syndromes, which meet each of the five criteria mentioned above and where prophylactic surgery is most useful, are the type 2 multiple endocrine neoplasia (MEN) syndromes: MEN2A, MEN2B, and the related familial medullary thyroid carcinoma. An additional benefit of the Human Genome Project, has been the development of pharmacologic and biologic compounds that block the metabolic pathway(s) activated by specific genetic mutations. Many of these compounds have shown efficacy in patients with locally advanced or metastatic cancers, and there is the likelihood that they will prove beneficial in preventing the outgrowth of malignant cells in patients destined to develop a hereditary cancer.

Medullary thyroid carcinoma--update and present management controversies

INTRODUCTION

Medullary thyroid carcinoma (MTC) is a rare thyroid malignancy arising from the parafollicular C cells. It accounts for 5-10% of thyroid malignancies and occurs in sporadic and hereditary forms. There are still many controversial aspects relating to the diagnosis and management of this unusual tumour in its various forms. The present article addresses the more important of these issues.

METHODS

A literature review was performed using Pubmed database combined with additional original papers obtained from citations in those articles identified in the original literature search. Only those articles which related specifically to the controversial issues addressed in this review were included.

RESULTS

Genetically determined tumours constitute approximately 25% of MTC and have special clinical interest because of their association with other endocrinopathies including phaeochromocytoma and hyperparathyroidism in the multiple endocrine neoplasia syndromes (MEN IIa and MEN IIb). Familial medullary thyroid carcinoma (FMTC) is a rare form not associated with any other endocrinopathies. The genetic basis for these familial tumours derives from a series of missense germline mutations in the RET protooncogene. Genetic testing by DNA analysis facilitates identification of family members at risk who can now be offered early 'prophylactic thyroidectomy' with an increased prospect of surgical success and long-term survival. MTC is a tumour which does not take up radioactive iodine, is relatively radioresistant and poorly responsive to chemotherapy. Therefore, surgery is the only treatment which can offer the prospect of cure. Total thyroidectomy with central and lateral nodal dissection can achieve biochemical cure (normocalcitonaemia) in more than 80% of cases. Compartmental orientated microdissection of cervical nodes has significantly improved the results of primary surgery but even so a group of 20% of patients will prove to have recurrent or residual disease. These cases require detailed investigation by a variety of techniques including ultrasound, cross-sectional imaging, nuclear imaging and laparoscopy with liver biopsy to exclude disseminated disease and select those patients who can be offered a prospect of cure by further neck surgery. Such an approach may be associated with successful normalisation of calcitonin levels in about 40%.

CONCLUSIONS

It is hoped that in the near future new medical therapies may become available to treat MTC which still has a 10-year survival of only 60-80% in spite of the application of meticulous surgical techniques.

Cyclooxygenase-2 expression in medullary thyroid carcinoma

BACKGROUND

Recent studies have demonstrated that cyclooxygenase-2 (COX-2) expression is associated with the carcinogenesis of numerous neoplasms. The aim of this study was to evaluate the role of COX-2 in medullary thyroid carcinoma (MTC).

METHODS

Tissue specimens of thyroid neoplasms were obtained from 22 patients with MTC and 15 control subjects with nonmalignant thyroid specimens.

RESULTS

This immunohistochemical study confirms the presence of COX-2 in a significant number of MTCs. A large area of staining was noted in only 2 patients in the control group (13%) compared with 18 (82%) in the medullary carcinoma group. On a scale of 0 to 3, the average area of positive staining measured 2.35 in the study group and 0.9 in the control group (p < .0001). The average intensity of staining on a scale of 0 to 5 (deep brown) was 2.15 and 0.8 mm, respectively (p < .001).

CONCLUSION

COX-2 is expressed significantly in MTC including a larger area of staining and greater intensity than in nonmalignant thyroid tissue. These findings may have important treatment implications for the use of COX-2 inhibitors in patients with MTC.

Medullary Thyroid Cancer

The goal in managing patients who have MTC is to detect and surgically remove disease at an early stage. Tumor marker-based biochemical screening and DNA-based genetic screening have created the opportunity for effective prophylactic surgery in patients at risk for hereditary MTC. Complete surgical resection is critical for cure because cervical reoperation for persistent or recurrent disease benefits only select patients. With the advent of therapies that target the RET-activated pathways, new hope may be emerging for patients who have locally advanced or metastatic disease.

Value of routine measurement of serum calcitonin concentrations in patients with nodular thyroid disease: A multicenter study

BACKGROUND

The routine measurement of serum calcitonin (CT) has been proposed for patients with nodular thyroid disease (NTD), to detect unsuspected medullary thyroid carcinoma (MTC) before surgery.

OBJECTIVE

To assess the prevalence of hypercalcitoninemia and MTC in NTD patients; to compare the ability of CT measurement and fine needle aspiration cytology (FNAC) to predict MTC; to identify age groups of NTD patients who should be better candidates than others to undergo routine measurement of CT.

PATIENTS AND METHODS

1425 consecutive patients, referred from April 1, 2003, through March 31, 2004, to four Italian endocrine centers due to NTD, were grouped depending on age, and underwent basal and, in some cases, pentagastrin (Pg)-stimulated CT measurement, FNAC and, when indicated, surgery. Serum CT concentrations were measured by an immunoluminometric assay (ILMA).

RESULTS

Hypercalcitoninemia was found in 23 out of 1425 patients. MTC was discovered in 9 patients, all >40 yr old and showing high CT levels. Sensitivity of basal and Pg-stimulated CT to predict MTC before surgery was 100% for both tests, whereas specificity was 95 and 93%, respectively. CT specificity reached 100% when a cutoff value of 20 pg/ml was taken. FNAC showed an overall 86% sensitivity. When >10 mm MTC nodules were considered, FNAC sensitivity approached 100%. On the contrary, a correct cytological diagnosis was obtained in only one out of five patients with <10 mm MTC nodules (microMTC); in one patient with histologically proved microMTC, FNAC even demonstrated a benign lesion. Hypercalcitoninemia or MTC were associated with chronic thyroiditis in 30 or 33% of cases, respectively. C-cell hyperplasia was found in 57% of hypercalcitoninemic patients without MTC.

CONCLUSIONS

Basal CT measurement detects elevated CT values in 1.6% of NTD patients. Although CT is not a specific marker of MTC, its routine measurement represents a useful tool in the pre-operative evaluation of NTD patients, particularly those >40 yr old presenting with nodules <10 mm, even when FNAC does not show malignant features. To our knowledge, this is the first trial using ILMA to assess the ability of pre-operative CT measurement to predict MTC in a large series of NTD patients.

Neoplasia endócrina múltipla tipo 2

O termo neoplasia endócrina múltipla tipo 2 (NEM 2) foi sugerido em 1968, por Steiner e cols., para diferenciar a síndrome clínica caracterizada pela presença de carcinoma medular de tireóide (CMT), feocromocitoma e hiperparatireoidismo, então denominada síndrome de Sipple, da síndrome de Wermer ou NEM tipo 1, que acomete as glândulas paratireóides, pâncreas e hipófise. Sizemore e cols. (1974) complementaram a diferenciação através da classificação da NEM 2 em 2 subgupos: pacientes com CMT, feocromocitoma, hiperparatireoidismo e aparência normal (NEM 2A) e pacientes sem acometimento das paratireóides e fenótipo caracterizado por ganglioneuromatose intestinal e hábitos marfanóides (NEM 2B). CMT é usualmente o primeiro tumor a ser diagnosticado. O diagnóstico do CMT determina que seja avaliada a extensão da doença e rastreamento do feocromocitoma e hiperparatireoidismo. O diagnóstico de CMT esporádico ou hereditário é realizado através da análise molecular do proto-oncogene RET. Neste artigo são discutidos os aspectos fisiopatológicos, as anormalidades genéticas e os aspectos clínicos da NEM 2. A abordagem diagnóstica e terapêutica nos indivíduos afetados, carreadores assintomáticos e familiares em risco também são discutidos. Os avanços relacionados ao rastreamento genético e intervenção precoce permitiram uma melhoria no prognóstico a longo prazo. No entanto, ainda não dispomos de tratamento eficaz para doença metastática.

RET proto-oncogene: a review and update of genotype-phenotype correlations in hereditary medullary thyroid cancer and associated endocrine tumors

Hereditary medullary thyroid carcinoma (MTC) is caused by autosomal dominant gain-of-function mutations in the RET proto-oncogene. Associations between specific RET mutations (genotype) and the aggressiveness of MTC and presence or absence of other endocrine neoplasms (phenotype) are well documented. Mutations in six exons (10, 11, 13, 14, 15, and 16) located in either cysteine-rich or tyrosine kinase domains cause one of three distinctive clinical subtypes: familial MTC, multiple endocrine neoplasia (MEN) type 2A (including variants with Hirschsprung's disease and cutaneous lichen amyloidosis), and MEN 2B. Hallmarks of MEN 2A include MTC, pheochromocytoma, and hyperparathyroidism. MEN 2B is associated with an earlier onset of MTC and pheochromocytoma, the absence of hyperparathyroidism, and the presence of striking physical stigmata (e.g., coarse facies, ganglioneuromatosis, and marfanoid habitus). Familial MTC is not associated with other endocrine neoplasms; however, the accurate distinction between familial MTC and MEN 2A may be difficult in kindreds with small size, incomplete histories, or a predominance of young individuals who may not have yet fully manifested the syndrome. Genetic testing detects greater than 95% of mutation carriers and is considered the standard of care for all first-degree relatives of patients with newly diagnosed MTC. Recommendations on the timing of prophylactic thyroidectomy and the extent of surgery are based upon a model that utilizes genotype- phenotype correlations to stratify mutations into three risk levels.

Single Center Experience in Primary Surgery for Medullary Thyroid Carcinoma

Medullary thyroid carcinoma (MTC) is a rare disease, and most studies are either based on small numbers or multicenter studies with their inherent difficulties. Since 1995, a total of 440 patients with MTC underwent surgery in our clinic. A primary operation was performed in 188 patients (43% of 440). In 60 patients, the primary operation was performed because of a germline RET mutation ("prophylactic surgery"). Most (84%, 158/188) of the patients had pathologic calcitonin levels. Notably, MTC was found in almost 10% (3/30) of patients with normal calcitonin levels. However, all patients with lymph node metastases (LNMs) had elevated calcitonin levels. Total thyroidectomy (TTx) was performed in all patients. Lymph node dissection (LND) was performed at various extensions: one-compartment LND in 35% (66/188), three-compartment LND in 31% (58/188), and four-compartment LND in 29% (22/188). In general, lymph node dissection increased the likelihood of complications. LNM and distant metastases (DM) correlated with the extent of the primary tumor (pT category). The presence of LNM ranged from 17% (pT1 tumor) to 100% (pT4 tumor), whereas the presence of DM ranged from 0% (pT1 tumor) to 81% (pT4 tumor). Biochemical cure (normal calcitonin levels) was obtained in 72% (137/188) of patients. All 60 patients undergoing prophylactic surgery (tumor stage pT0/pT1) were biochemically cured. In contrast, only 60% (77/128) of the remaining patients were cured. The data suggest that primary surgery should be scheduled as soon as possible to treat patients at a node-negative stage. In the case of normal basal and elevated stimulated calcitonin levels, TTx and cervicocentral LND is recommended. If the basal calcitonin level is elevated, LND should include the cervicolateral compartment.

Impact of 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) in patients with biochemical evidence of recurrent or residual medullary thyroid cancer

BACKGROUND

Conventional imaging such as with (99m)Tc(V)dimercaptosunnic acid (DMSA), (111)In-octreotide scintigraphy, computed tomography (CT), and magnetic resonance imaging (MRI) rarely localizes occult medullary thyroid cancer (MTC). The role of (18)F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) is not well defined. The aim of this study was to examine the usefulness of postoperative FDG-PET in localizing MTC metastases.

METHODS

FDG-PET was performed in 26 patients with elevated serum tumor markers after total thyroidectomy with central compartment dissection and additional neck dissection on indication. Patient- and lesion-based results were compared with the findings of conventional nuclear imaging and validated by morphological imaging (CT, MRI, ultrasonography), including bone scintigraphy and pathology when possible. Clinical impact was evaluated.

RESULTS

FDG-PET detected foci in 50% of patients with lesion-based sensitivity of 96%. (111)In-octreotide detected foci in 19% with sensitivity of 41%, and (99m)Tc(V)DMSA scintigraphy and morphological imaging detected foci in 21% and 40%, respectively, with sensitivity of 57% and 87%. No lesions were found in 11 patients (42%). Positive FDG-PET findings led to surgical intervention in nine patients (35%). They all underwent surgery for removal of residual tumor or metastases. One patient achieved disease-free status. In all patients who underwent surgery, serum calcitonin levels were reduced by an average of 58 +/- 31%.

CONCLUSIONS

For detection of occult MTC lesions, FDG-PET is superior to conventional nuclear imaging and is the best detection method yet available. FDG-PET in postoperative follow-up has clinical value and may be used for guiding reoperation and additional morphological imaging preoperatively.

Diagnosis and management of medullary thyroid carcinoma

Successful treatment of MTC depends heavily on early diagnosis and treatment. Often, this is not possible for sporadic MTC; however, genetic testing for hereditary MTC makes this possible if genetic carriers have surgery before C cells undergo malignant transformation. All patients who have MTC should be tested for RET mutations, including putative sporadic cases. The leukocytes of suspected carriers and sporadic MTC cases should be tested for MEN2-associated germ-line mutations by polymerase chain reaction amplification of the appropriate RET gene exons, including 10, 11,13, 14, 15, and 16 (see Table I). When a RET mutation is found, all first-degree relatives must be screened to determine which individuals carry the gene. If these exons are negative, the other 15 should be sequenced because a small risk of hereditary MTC remains if no germ-line mutation is found. The probability that a first-degree relative will inherit an autosomal dominant gene for MTC from an individual who has sporadic MTC in whom no germ-line mutation is found is 0.18% . Patients who have MEN2B or RET codon 883 or 918 mutation should have a total thyroidectomy within the first 6 months of life, preferably within the first month of life. Patients who have 634 mutations, which account for approximately 70% of all MTC mutations, should undergo thyroidectomy by age 5 years. The recommendations for the timing of prophylactic thyroidectomy are not consistent for the less common mutations (see Table 2). There is a balance between performing prophylactic thyroidectomy earlier than at the youngest age at with MTC has been reported to occur for a specific RET mutation (see Fig. 3 and Table 2) and the complications of thyroidectomy, including permanent hypoparathyroidism and laryngeal nerve damage. Preoperative measurement of plasma free metanephrine and neck ultrasonography always should be done if the diagnosis of MTC is known preoperatively. Initial treatment of MTC is total thyroidectomy, regardless of its genetic type or putative sporadic nature, because surgery offers the only chance for a cure. Treatment with 1311 has no place in the management of MTC. Plasma CT measurements provide an accurate estimate of tumor burden and are especially useful in identifying patients who have residual tumor. Pentagastrin- or calcium-stimulated plasma CT testing is useful in identifying CCH or early MTC in carriers of RET mutations that are associated with late onset MTC. Pheochromocytoma may occur before or after MTC and is an important cause of mortality, even in young patients. HPT is an important aspect of MEN2A and requires surgery according to current guidelines for the management of primary HPT. Early thyroidectomy and appropriate management of pheochromocytoma clearly have modified the course of this disease, but more research is necessary in kindreds who have rare MTC mutations. Moreover, new treatments for widespread MTC are necessary because current chemotherapy agents offer little benefit. New drugs that lock the action of tyrosine kinase offer some hope.

The diagnosis and medical management of advanced neuroendocrine tumors

Neuroendocrine tumors (NETs) constitute a heterogeneous group of neoplasms that originate from endocrine glands such as the pituitary, the parathyroids, and the (neuroendocrine) adrenal, as well as endocrine islets within glandular tissue (thyroid or pancreatic) and cells dispersed between exocrine cells, such as endocrine cells of the digestive (gastroenteropancreatic) and respiratory tracts. Conventionally, NETs may present with a wide variety of functional or nonfunctional endocrine syndromes and may be familial and have other associated tumors. Assessment of specific or general tumor markers offers high sensitivity in establishing the diagnosis and can also have prognostic significance. Imaging modalities include endoscopic ultrasonography, computed tomography and magnetic resonance imaging, and particularly, scintigraphy with somatostatin analogs and metaiodobenzylguanidine. Successful treatment of disseminated NETs requires a multimodal approach; radical tumor surgery may be curative but is rarely possible. Well-differentiated and slow-growing gastroenteropancreatic tumors should be treated with somatostatin analogs or alpha-interferon, with chemotherapy being reserved for poorly differentiated and progressive tumors. Therapy with radionuclides may be used for tumors exhibiting uptake to a diagnostic scan, either after surgery to eradicate microscopic residual disease or later if conventional treatment or biotherapy fails. Maintenance of the quality of life should be a priority, particularly because patients with disseminated disease may experience prolonged survival.

Incidentally found medullary thyroid cancer: treatment rationale for small tumors

The object of this study was to assess the extent of surgery required for small sporadic medullary thyroid cancers (sMTCs). We retrospectively studied 261 patients with MTCs treated in our institution between 1986 and 2002 and identified 15 patients with small pT1 or pT2 sMTCs. The tumors were diagnosed incidentally, so surgical therapy was less than total thyroidectomy. Total thyroidectomy with or without neck dissection was applied to all other patients as standard surgical treatment of care. Patients were systematically followed up by postoperative ultrasonography, calcitonin, carcinoembryonic antigen levels, and pentagastrin stimulation tests. On long-term follow-up over a period of 4.6 years, the rate of biochemical cure in these patients who underwent less than total thyroidectomy for a sporadic incidentally diagnosed tumor was 100%. We concluded that completion thyroidectomy and neck dissection are not mandatory in patients in whom a solitary small sMTC is incidentally discovered by histologic diagnosis following operation so long as a genetic background is excluded. Nevertheless, such patients require systematic careful long-term follow-up.

Molecular genotyping of medullary thyroid carcinoma can predict tumor recurrence

Medullary thyroid carcinoma can have an aggressive behavior, and little is known about the molecular basis for clinical outcome. Defining risk of recurrent or metastatic disease is difficult, and it has been limited to clinical and pathologic features, such as advanced age, cervical lymph node metastases, and stage at presentation. Using microdissection and genotyping, we studied 11 cases of medullary carcinoma for allelic losses in a panel of known tumor suppressor genes. The tumor suppressor genes with the most frequent allelic losses were NF2, l-myc, and p53 (75%, 44%, and 44%, respectively). The average frequency of allelic loss across all tumors was 44% and was higher in tumors that recurred. A combination of previously described high-risk variables (increased patient age and cervical lymph node metastases) with the frequency of allelic loss yielded a high-risk group, in which 6 of 6 patients recurred, and a low-risk group, in which 0 of 5 patients recurred (P = 0.004). Frequency of allelic loss in tumor suppressor genes may provide a useful adjunctive prognostic test in medullary thyroid carcinoma.

Carcinoma medular de tireóide: aspectos moleculares, clínico-oncológicos e terapêuticos

O carcinoma medular de tireóide (CMT) pode ocorrer na forma esporádica ou familiar. O CMT hereditário é parte das síndromes de neoplasia endócrina múltipla (NEM) 2A e 2B, carcinoma medular de tireóide familiar (CMTF) ou outras formas. Mutações de linhagem germinativa do proto-oncogene RET causam a forma hereditária da neoplasia e os testes genéticos atualmente disponíveis formam a base para o manejo adequado da hereditariedade do tumor, visto que o diagnóstico precoce melhora significativamente o prognóstico no indivíduo afetado e nos carreadores. Nos últimos anos, vários estudos têm demonstrado uma correlação entre mutações codon-específica do RET e os diferentes fenótipos da NEM 2A, que pode, em parte, ser explicada por diferenças na intensidade da indução da dimerização do receptor. No presente artigo, revisamos os avanços nos mecanismos moleculares, diagnóstico e tratamento, bem como relatamos a nossa experiência no manejo dessa forma rara de neoplasia tireoidiana.

[The importance of lymph node dissection in medullary thyroid macrocarcinomas]

Medullary thyroid carcinoma (MTC) is often regarded as good medium-term forecast. The 5- and 10-years survival rates are, respectively, appraised at 78-85% and 70-78%. These rates take no care, however, of the fact that 50-56% of the patients keep a pathological calcitonine (CT) level giving evidence of an evolutive disease. The treatment is based on the total thyroidectomy and cervical lymphadectomy. This treatment remains often incomplete and the results of reintervention are disappointing.

AIM OF THE STUDY

About 48 patients, we wanted to demonstrate the importance of a complete lymph node dissection performed in the neck as soon as possible.

PATIENTS AND METHODS

Between 1979 and 2000, 48 patients were treated for macroMTC (size >1 cm). The duration of follow-up was of 1-29 years (mean 9.3 years). The complete (central and lateral) neck dissection was initially made only in 22 cases. The selected criterion to assess the result was the normalization of the basal CT level.

RESULTS

The rate of node involvement was 66.6% if the complete lymphadectomies (n = 22), the secondary neck dissections (n = 15), the incomplete (n = 10) and not made lymphadectomies (n = 2) were gathered. In case of primary or secondary complete lymphadectomies, the rate of node involvement was 81%. The 22 primary complete lymphadectomies performed in 13 patients (59%) allowed to normalize the basal CT level and among 17 (77.2%) to decrease this rate over 90%. All the incomplete neck dissection failed in case of positive nodes.

CONCLUSION

The frequency of node involvement in macroMTC is about 80%. It does not have a preferential territory and the bilaterality is frequent (28-49%): that justifies a bilateral complete neck dissection. Initial surgical treatment seems essential in regard to the rate of normalization of basal CT level, which is, when a first complete lymphadectomy is done and in case of iterative surgery, respectively 59 and 26.6%. A complete lymphadectomy is still too rarely carried out: 22 times (45.8%) in our own experience and from 14 to 42% in the literature.

Calcitonin precursor levels in human medullary thyroid carcinoma

DESIGN

The hormonal serum marker for the presence and course of patients with medullary thyroid cancer (MTC) is the mature calcitonin (CT) peptide. Other CALC-1 gene products such as the 116-amino acid polypeptide prohormone, procalcitonin, as well as its component calcitonin precursors (CTpr) may also be increased in their sera. We performed a study to evaluate the clinical utility of serum levels CTpr in these patients.

METHODS

Twenty-one patients with MTC (9 males, 12 females; 23-76 years of age) were evaluated. The diagnosis was confirmed by histologic examination, except for 2 (a proven RET mutation plus an abnormal pentagastrin-stimulated CT level). Nine patients had postoperative hypercalcitoninemia and 3 of these died. The specific assay for mature CT was a commercial immunoradiometric assay (hCT-IRMA); the immunoluminometric assay for CTpr (B.R.A.H.M.S Diagnostica, Berlin, Germany) detects intact procalcitonin and the free CT:CT carboxypeptide-1.

RESULTS

All patients had detectable serum CTpr. These levels considerably exceeded those of mature CT, averaging 7.6-fold greater. CTpr levels correlated positively with mature CT (r = 0.61; p < 0.001). After pentagastrin administration, there was a parallelism of response between the two assays. Whenever there were known metastases, CTpr increased markedly.

CONCLUSION

This study demonstrates the universal presence of CTpr in the blood of patients with MTC. The measurement of these peptides may offer a new dimension to the clinical evaluation of this malignancy.

Potential Absence of Prognostic Implications of Severe Preoperative Hypercalcitoninemia in Medullary Thyroid Carcinoma

OBJECTIVE

To evaluate preoperative hypercalcitonine-mia further as a marker of prognosis in patients with medullary thyroid carcinoma (MTC).

METHODS

We reviewed the clinical and laboratory data in six patients (four men and two women, 39 to 76 years old)--three with sporadic MTC, one with familial MTC, and two with multiple endocrine neoplasia type 2A--who had preoperative basal serum calcitonin levels of 400 to 16,000 pg/mL (normal, 0 to 19). Pentagastrin stimulation was performed in patients who had preoperative basal calcitonin levels less than 1,000 pg/mL, and responses ranged from 2,600 to 8,500 pg/mL. Thyroidectomy revealed intrathyroidal MTC in four patients; MTC and nodal metastatic lesions were present in two. The tumor cells were immunoreactive with anti-calcitonin immunoperoxidase staining.

RESULTS

Serum calcitonin and carcinoembryonic antigen levels were normal postoperatively. In serial postoperative evaluation during a follow-up period of 2 to 9 years, stimulated peak plasma calcitonin levels after pentagastrin or calcium infusion were normal (in five patients) or near normal (in one patient), without clinical evidence of recurrent disease. The two patients with nodal metastatic disease have had normal calcitonin levels during a mean duration of follow-up of approximately 3 years.

CONCLUSION

Pronounced preoperative hypercalci-toninemia does not necessarily preclude a favorable short-term outcome in patients with MTC.

A population-based analysis of survival factors in differentiated and medullary thyroid carcinoma

OBJECTIVE

The study purpose was to determine survival and prognostic factors for differentiated thyroid carcinoma (DTC).

METHODS

Cases of DTC were extracted from the Surveillance, Epidemiology and End Results database from 1988 through 1998. Kaplan-Meier survival analysis was conducted for papillary, follicular, and medullary histologies. Cox proportional hazard analysis was used to examine the influence of age, gender, tumor size, local extension, and cervical node involvement on overall survival.

RESULTS

A total of 18,118 cases were identified, including 15,820 (87.3%) papillary carcinomas, 1799 (9.9%) follicular carcinomas, and 499 (2.8%) medullary carcinomas. Mean survival (10-year survival) was 122 (87.7%), 117 (80.2%), and 108 (73.7%) months for papillary, follicular, and medullary tumors, respectively. For each histology, increasing age, male gender, and degree of local extension substantially reduced survival. Cervical metastasis did not influence survival for papillary or follicular carcinomas but approached significance for medullary carcinoma (P = 0.065).

CONCLUSIONS

Degree of local extension in thyroid carcinoma should be subclassified to more accurately determine prognosis. Treatment of the neck should be considered for medullary thyroid carcinoma.

Prolonged survival of a patient with multiple endocrine neoplasia type 2b and stage IV medullary thyroid carcinoma

OBJECTIVE

To present a case of multiple endocrine neoplasia type 2B (MEN2B) with a prolonged course.

METHODS

We describe the clinical, laboratory, and radiologic findings in a patient with MEN2B and review the various interventions during a period of approximately 3 decades.

RESULTS

In 1962, a 19-year-old man with a marfanoid body habitus presented with multiple thyroid nodules and neurofibromas of the tongue. Total thyroidectomy demonstrated multicentric medullary thyroid carcinoma with cervical lymph node metastatic involvement. At the time of the first description of the MEN2B syndrome, the patient was enrolled in a surveillance program. An increase in urinary metanephrines resulted in bilateral adrenalectomy for multinodular pheochromocytoma in 1972. Increased serum calcitonin levels and the appearance of cervical lymphadenopathy led to modified radical neck dissection 12 years after the initial diagnosis of medullary thyroid carcinoma. In 1975, angiography revealed extensive hepatic lesions metastatic from the medullary thyroid carcinoma; this finding was confirmed by open liver biopsy in 1988. The patient lived 16 years after the initial diagnosis of liver metastatic disease and died 29 years after the initial examination.

CONCLUSION

The 3-decade course of this patient not only represents a classic case of MEN2B but also allows us to present the history of this disease from its discovery to the current era of genetic testing and exemplifies the possibility of long-term survival in a patient with liver metastatic involvement from medullary thyroid carcinoma.

Recombinant TSH-stimulated, radioguided differentiated thyroid carcinoma surgery

A novel approach to locating and surgically resecting occult metastatic foci in a 25-year-old female with a history of total thyroidectomy for differentiated thyroid carcinoma was attempted. Two iodine-131 (131I) body scans were performed: one after the patient underwent a 2-3 week thyroxine withdrawal, and another the following week utilizing recombinant TSH-stimulation. Then the patient was treated with 151 mCi of 131I, and 2 weeks later, without further hormonal manipulation, she had radioguided surgery. The two diagnostic 131I body scans were negative, but the post-therapy scan was positive. Two weeks later after pre-operative skin marking, radioguided surgery localized metastatic foci in the central compartment neck just dorsal to the suprasternal notch. No other foci were identified with the probe at surgery. At pathology, 2 of the 12 nodes were positive, as well as a 1 mm metastatic focus in the fat. Provocative imaging protocols, aggressive radioiodine therapy, and the novel use of radioguided surgery to attempt a cure in an 131I image-negative metastatic thyroid carcinoma patient was performed. No other cases using these combined diagnostic and therapeutic efforts have been reported in the literature.

Concurrent lymph node metastases of medullary and papillary thyroid carcinoma in a case with RET oncogene germline mutation

We report the case of a 72 yr-old woman who underwent total thyroidectomy and resection of neck lymph nodes because of a firm nodule in the right lobe, which was consistent with medullary thyroid carcinoma (MTC) on cytological examination. Histology showed multifocal bilateral MTC; a 2 mm papillary thyroid carcinoma (PTC) was also detected in the right lobe, next to a focus of MTC; five cervical lymph nodes contained MTC. In one right perithyroidal lymph node, concurrent metastases of MTC and PTC were demonstrated. DNA analysis showed a point mutation in exon 14 at codon 804 of the RET proto-oncogene locus, as frequently found in cases of familial MTC (FMTC). To our knowledge, this case represents the first documented case of concurrent lymph node metastases of MTC and PTC in a patient with RET proto-oncogene germline mutation. We report this unique case, discuss related thyroid malignancies, and suggest possible underlying pathogenetic mechanisms.

Rastreamento genético do carcinoma medular de tireóide: identificação de mutações no proto-oncogene ret

O carcinoma medular de tireóide (CMT) pode apresentar-se na forma esporádica (75%) ou hereditária (25%) como componente das síndromes de neoplasia endócrina múltipla (NEM2A e 2B), carcinoma medular de tireóide familiar (CMTF) ou outros. Diferentes mutações no proto-oncogene Ret foram identificadas e estudos recentes sugerem uma correlação entre o genótipo-fenótipo. O presente estudo realizou a análise molecular do Ret em indivíduos com CMT e avaliou a correlação genótipo-fenótipo nos afetados e seus familiares. Foram incluídos 48 indivíduos com diagnóstico histopatológico e imunohistoquímico de CMT, sendo 7 esporádicos e 41 hereditários, provenientes de 14 famílias independentes. DNA genômico foi extraído de leucócitos periféricos e os exons 10, 11, 13, 14 e/ou 16 do Ret amplificados por PCR. As mutações foram identificadas por SSCP, restrição enzimática, e/ou seqüenciamento. Das famílias com CMT hereditário, 7 apresentavam NEM2A, 2 NEM2A associada à líquen amilóide cutâneo (CLA), 2 NEM2B, 2 CMTF e 1 como outros. Em 6 famílias com NEM2A, a mutação estava presente no codon 634, troca de TGC->CGC ou TGC->TAC. Uma família com NEM2A apresentava mutação no codon 618 (TGC->CGC). Ambas famílias com CMTF e nos casos de NEM2A+CLA, a mutação também ocorreu no codon 634 (TGC->CGC). Nos indivíduos afetados com NEM2B foi detectada uma mutação de novo no códon 918 (ATG->ACG). Na família classificada como outros, a mutação localizava-se no códon 634 (TGC->TAC). O diagnóstico molecular identificou mutações em todos os indivíduos com história de doença hereditária, em 8 carreadores sem evidência clínica de neoplasia, e em 2 indivíduos com CMT aparentemente esporádico. Nossos resultados confirmam dados da literatura e demonstram que o rastreamento genético é fundamental na conduta terapêutica.

Polymerase chain reaction in the detection of tumor cells: new approaches in diagnosis and follow-up of patients with thyroid cancer

Thyroid cancers are the most common endocrine malignancies and are being diagnosed with increasing frequency. In addition to other measures, diagnosis is based on fine-needle aspiration cytology examination. Recently, new assays using reverse transcription-polymerase chain reaction (PCR) are being tested to improve sensitivity and specificity of primary diagnosis and detection of recurrent thyroid cancer. In the preoperative diagnosis of thyroid cancer, several tissue- and/or tumor-specific mRNA have been described and in several cases, a higher sensitivity and specificity could be achieved using molecular techniques compared to conventional methods. In the postoperative follow-up of patients with thyroid cancer, conflicting data have been published and the use of PCR techniques revealed several problems of the molecular approach, which are based on some technical as well as biologic limitations. Despite these problems, which are discussed in detail in this review, molecular techniques may nevertheless improve the sensitivity and accuracy of fine-needle aspiration of thyroid nodules, fine-needle aspiration of metastases, and detection of recurrent disease in peripheral blood samples.

Presurgical assessment of the tumor burden of familial medullary thyroid carcinoma by calcitonin testing

BACKGROUND

Early diagnosis of familial medullary thyroid carcinoma (MTC) is currently done by genetic analysis. These techniques have replaced calcitonin stimulation testing, which was previously used for this purpose. Some studies suggest a relationship between MTC spread and calcitonin levels. The aim of this study was to assess whether the tumor burden of MTC associated with multiple endocrine neoplasia type 2A (MEN 2A) syndrome can be estimated from the plasma calcitonin values before surgery.

STUDY DESIGN

We retrospectively studied the relationship of basal and peak calcitonin values before thyroidectomy with histopathologic findings in 53 patients with MEN 2A syndrome from 14 families. The MTC was classified according to TNM staging. Analysis of variance was used for statistical analysis complemented with equality contrasts for pairs of means by the least significant difference method with a Student's t-test and with the Bonferroni's adjustment.

RESULTS

A positive association was found between tumor stage and basal and peak calcitonin levels. There were significant differences between the following: mean basal concentrations of patients with C cell hyperplasia (CCH) (34.3 pg/mL) and TNM stage II (1,097.4 pg/mL), p < 0.01; CCH and TNM stage III (2,940.8 pg/mL), p < 0.001; TNM stage I (165.3 pg/mL) and stage II (1,097.4 pg/mL), p < 0.01, and between TNM stages I and III, p < 0.001. Poststimulation mean concentrations were different between CCH (48.7 pg/mL) and TNM I (514.2 pg/mL), p < 0.001.

CONCLUSIONS

Preoperative calcitonin testing may be useful for assessing tumor spread and should be considered when deciding the extent of surgery for MEN 2A MTC.

Comparison of Two Provocative Tests for Calcitonin in Medullary Thyroid Carcinoma: Omeprazole vs Pentagastrin

Background: Provocative tests for calcitonin (CT) are fundamental in the diagnosis and follow-up of C-cell disease and in the detection of hereditary medullary thyroid carcinoma (MTC) carriers with unknown RET mutations. A recent report has proposed omeprazole, which can increase endogenous gastrin (GT), as a new provocative test for MTC.

Methods: We compared the omeprazole test (20 mg twice a day for 4 days) to the pentagastrin test (0.5 μg/kg of body weight) for the diagnosis and management of MTC. Twenty healthy individuals and 20 MTC patients with mildly or moderately increased basal CT serum concentrations underwent the pentagastrin and omeprazole tests.

Results: In MTC patients, the pentagastrin test produced a significantly higher increase in serum CT than did omeprazole. After the pentagastrin injection, several patients reported unpleasant side effects, including substantial tightness in 38 of 40 participants. No adverse effects were observed during the omeprazole test. A significant direct correlation was recorded between CT% (ratio of CT peak to basal value × 100) and GT% (ratio of GT peak to basal value × 100) during the omeprazole test in MTC patients (r = 0.73; P &lt;0.001).

Conclusions: In spite of several adverse effects, pentagastrin remains the best provocative test for the diagnosis of MTC. Omeprazole may be useful when pentagastrin is contraindicated or refused because of the unpleasant side effects, but further validation is needed.

Prophylactic thyroidectomy in MEN 2A syndrome: experience in a single center

BACKGROUND

Genetic study of the RET proto-oncogene has modified the management, treatment, and prognosis of medullary thyroid carcinoma (MTC), multiple endocrine neoplasia 2A (MEN 2A), for patients with less advanced tumor stages. Classically, the diagnosis was based on an increase in basal and poststimulus peak calcitonin (bCT and pCT). Prophylactic thyroidectomy, based on results of genetic testing, may reduce recurrences in MTC.

STUDY DESIGN

Of 82 MTC (MEN 2A) patients genetically diagnosed and surgically treated at our center, 22 received a prophylactic thyroidectomy (RET +, bCT and pCT with normal values and asymptomatic). We analyzed age, gender, phenotype, RET mutation, cervical ultrasound, laboratory tests (bCT, pCT, and CEA), surgery, histologic data, TNM, and followup.

RESULTS

The 22 patients belonged to 8 families with MTC (MEN 2A). Mean age was 15.2 years (range 5 to 36 years). The RET mutation in 21 patients was Cys-->Tyr and in the remaining patient both in codon 634 in exon 11. The median values of bCT and pCT were 38 pg/mL (range < 15 to 75 pg/mL) and 148.5 pg/mL (range < 15 to 250 pg/mL), respectively. Total thyroidectomy was performed in 8 patients (age < or = 10 years) and associated central neck dissection in 14 patients (age> 10 years). Histologic study showed 7 C-cell hyperplasias and 15 MTCs (8 bilateral); the median size was 0.2 cm (range < 0.1 to 0.7cm); 1 patient had metastatic adenopathies. According to TNM, 7 were stage 0, 14 were stage I, and 1 was stage III. Postsurgery bCT and pCT values were normal in all patients, with a curative rate of 100%. MTC patients compared with C-cell hyperplasia patients were older on average, had higher mean bCT, mean pCT, and mean CEA.

CONCLUSIONS

Prophylactic thyroidectomy based on genetic testing allows identification and treatment of patients at an early stage of the disease and decreases recurrence rates. pCT values above the upper limit of normal may be markers for the presence of MTC and should be considered in selecting operative procedures for these patients.